/*****************************************************************************
 * Licensed to the Apache Software Foundation (ASF) under one                *
 * or more contributor license agreements.  See the NOTICE file              *
 * distributed with this work for additional information                     *
 * regarding copyright ownership.  The ASF licenses this file                *
 * to you under the Apache License, Version 2.0 (the                         *
 * "License"); you may not use this file except in compliance                *
 * with the License.  You may obtain a copy of the License at                *
 *                                                                           *
 *     http://www.apache.org/licenses/LICENSE-2.0                            *
 *                                                                           *
 * Unless required by applicable law or agreed to in writing,                *
 * software distributed under the License is distributed on an               *
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY                    *
 * KIND, either express or implied.  See the License for the                 *
 * specific language governing permissions and limitations                   *
 * under the License.                                                        *
 *                                                                           *
 *                                                                           *
 * This file is part of the BeanShell Java Scripting distribution.           *
 * Documentation and updates may be found at http://www.beanshell.org/       *
 * Patrick Niemeyer (pat@pat.net)                                            *
 * Author of Learning Java, O'Reilly & Associates                            *
 *                                                                           *
 *****************************************************************************/


package bsh;

import java.lang.reflect.InvocationTargetException;
import java.io.PrintStream;

/**
    TargetError is an EvalError that wraps an exception thrown by the script
    (or by code called from the script).  TargetErrors indicate exceptions
    which can be caught within the script itself, whereas a general EvalError
    indicates that the script cannot be evaluated further for some reason.

    If the exception is caught within the script it is automatically unwrapped,
    so the code looks like normal Java code.  If the TargetError is thrown
    from the eval() or interpreter.eval() method it may be caught and unwrapped
    to determine what exception was thrown.
*/
public final class TargetError extends EvalError
{
    private final boolean inNativeCode;

    public TargetError(
        String msg, Throwable t, Node node, CallStack callstack,
        boolean inNativeCode )
    {
        super( msg, node, callstack, t );
        this.inNativeCode = inNativeCode;
    }

    public TargetError( Throwable t, Node node, CallStack callstack )
    {
        this("TargetError", t, node, callstack, false);
    }

    public synchronized Throwable getTarget()
    {
        // check for easy mistake
        final Throwable target = getCause();
        if(target instanceof InvocationTargetException)
            return target.getCause();
        else
            return target;
    }

    public synchronized String getMessage()
    {
        return super.getMessage()
            + "Caused by: " +
            printTargetError( getCause() );
    }

    public void printStackTrace( boolean debug, PrintStream out ) {
        if ( debug ) {
            super.printStackTrace( out );
            out.println("--- Target Stack Trace ---");
        }
        StackTraceElement[] st = getCause().getStackTrace();
        for ( StackTraceElement ste : st )
            if ( !ste.getClassName().contains("reflect") )
                out.println("        at "+ste);
            else break;
    }

    /** Generate a printable string showing the wrapped target exceptions.
     * @param t wrapped target exception
     * @return messages unwrapped */
    private synchronized String printTargetError( Throwable t ) {
        if (null == t) return "Cause is null";
        StringBuilder msgs = new StringBuilder(t.toString());
        while ( null != (t = t.getCause()) )
            msgs.append("\n").append(t.toString());
        return msgs.toString();
    }

    /**
        Return true if the TargetError was generated from native code.
        e.g. if the script called into a compiled java class which threw
        the excpetion.  We distinguish so that we can print the stack trace
        for the native code case... the stack trace would not be useful if
        the exception was generated by the script.  e.g. if the script
        explicitly threw an exception... (the stack trace would simply point
        to the bsh internals which generated the exception).
    */
    public boolean inNativeCode() {
        return inNativeCode;
    }
}

